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Merge tag 'scrub-livelock-prevention-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.8-mergeA

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xfs: prevent livelocks in xchk_iget

Prevent scrub from live locking in xchk_iget if there's a cycle in the
inobt by allocating an empty transaction.

This has been lightly tested with fstests.  Enjoy!

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'scrub-livelock-prevention-6.8_2023-12-06' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: make xchk_iget safer in the presence of corrupt inode btrees
This commit is contained in:
Chandan Babu R
2023-12-07 14:15:26 +05:30
parent 9f334526ee 3f113c2739
commit dec0224bae
3 changed files with 31 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
fs/xfs/scrub/common.c
View File

@@ -733,6 +733,8 @@ xchk_iget(
xfs_ino_t inum,
struct xfs_inode **ipp)
{
ASSERT(sc->tp != NULL);
return xfs_iget(sc->mp, sc->tp, inum, XFS_IGET_UNTRUSTED, 0, ipp);
}
@@ -882,8 +884,8 @@ xchk_iget_for_scrubbing(
if (!xfs_verify_ino(sc->mp, sc->sm->sm_ino))
return -ENOENT;
/* Try a regular untrusted iget. */
error = xchk_iget(sc, sc->sm->sm_ino, &ip);
/* Try a safe untrusted iget. */
error = xchk_iget_safe(sc, sc->sm->sm_ino, &ip);
if (!error)
return xchk_install_handle_inode(sc, ip);
if (error == -ENOENT)

25
fs/xfs/scrub/common.h
View File

@@ -151,12 +151,37 @@ void xchk_iunlock(struct xfs_scrub *sc, unsigned int ilock_flags);
void xchk_buffer_recheck(struct xfs_scrub *sc, struct xfs_buf *bp);
/*
* Grab the inode at @inum. The caller must have created a scrub transaction
* so that we can confirm the inumber by walking the inobt and not deadlock on
* a loop in the inobt.
*/
int xchk_iget(struct xfs_scrub *sc, xfs_ino_t inum, struct xfs_inode **ipp);
int xchk_iget_agi(struct xfs_scrub *sc, xfs_ino_t inum,
struct xfs_buf **agi_bpp, struct xfs_inode **ipp);
void xchk_irele(struct xfs_scrub *sc, struct xfs_inode *ip);
int xchk_install_handle_inode(struct xfs_scrub *sc, struct xfs_inode *ip);
/*
* Safe version of (untrusted) xchk_iget that uses an empty transaction to
* avoid deadlocking on loops in the inobt. This should only be used in a
* scrub or repair setup routine, and only prior to grabbing a transaction.
*/
static inline int
xchk_iget_safe(struct xfs_scrub *sc, xfs_ino_t inum, struct xfs_inode **ipp)
{
int error;
ASSERT(sc->tp == NULL);
error = xchk_trans_alloc(sc, 0);
if (error)
return error;
error = xchk_iget(sc, inum, ipp);
xchk_trans_cancel(sc);
return error;
}
/*
* Don't bother cross-referencing if we already found corruption or cross
* referencing discrepancies.

4
fs/xfs/scrub/inode.c
View File

@@ -95,8 +95,8 @@ xchk_setup_inode(
if (!xfs_verify_ino(sc->mp, sc->sm->sm_ino))
return -ENOENT;
/* Try a regular untrusted iget. */
error = xchk_iget(sc, sc->sm->sm_ino, &ip);
/* Try a safe untrusted iget. */
error = xchk_iget_safe(sc, sc->sm->sm_ino, &ip);
if (!error)
return xchk_install_handle_iscrub(sc, ip);
if (error == -ENOENT)